JPH0368914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mastic adhesive composition, more specifically, a mastic adhesive composition that has excellent adhesion (adhesiveness) to steel plates coated with rust preventive oil or specially treated steel plates and is curable at low temperatures. Regarding. In recent years, along with the reduction in weight and diversification of automobiles, there has been a demand for an increase in the service life of car body steel plates, such as improved rust prevention. Under these circumstances, the steel sheets for automobile bodies have recently changed from conventional ones to thin-walled high-tensile strength steel sheets, and from the viewpoint of improving rust prevention and corrosion resistance, alloy plating treatment with other metals has been adopted instead of galvanized treatment. Specially treated steel sheets are increasingly being used. On the other hand, in the manufacturing and assembly of automobile bodies, the so-called knock-down method has been adopted, in which semi-finished products are sent to export destinations and assembled into finished products locally, and domestic automobile assembly and manufacturing also requires less paint due to energy consumption. The baking temperature is on a downward trend. In particular, specially treated steel sheets that are plated with zinc-nickel alloy and then subjected to chromate treatment are being adopted. Additionally, the baking temperature of the paint has been lowered from the conventional 150℃ or higher to 130℃. With these changes in the automobile industry, the required performance of various parts and materials on the car body assembly line is also changing dramatically.In particular, automobile bonnets, trunks, roofs, doors, etc. are made of two steel plates, an outer panel and an inner panel. The ends are fixed by spot welding, but due to the appearance of the car body, spot welding is not possible for fixing the outer and inner panels using vibration damping and
Adhesives are also used to reduce vibration noise.
This adhesive is a mastic adhesive, which adheres to a steel plate coated with anti-rust oil and hardens under paint drying and baking temperature conditions such as electrocoating paint.
Usually polyvinyl chloride plastisol or chloroprene mastic adhesives are used. but,
As mentioned above, with changes in automobile manufacturing conditions, there has been a desire for a mastic adhesive that cures at a low temperature of 130° C. and has excellent adhesive properties. Under such circumstances, conventional adhesion promoters include mixtures of epoxy resins and heat-activated latent curing agents (for example, one or more of urea-based, imidazole-based, hydrazine-based, and guanidine-based compounds), phenolic resins, and polyamides. Mastic adhesive compositions containing resins, organic alkoxysilane compounds, blocking isocyanates, etc. have been developed. However, although these bond well when applied to high bake-hardening temperatures or to conventional zinc-nickel alloy plated steel sheets, when the bake-hardening temperature drops to 130°C, zinc-nickel and chromate treatments The adhesion to the specially treated steel plate was completely inadequate, and it had not been put to practical use. Therefore, the present inventors developed a mastic adhesive that hardens even at a low temperature of around 130°C and exhibits excellent adhesion to zinc-nickel alloy plating coated with anti-corrosion oil and specially treated steel plate treated with chromat. We conducted intensive research to develop polyvinyl chloride,
In mastic adhesives consisting of synthetic rubber, plasticizers, and fillers, blocked isocyanates, liquid epoxy resins, and butadiene-acrylonitrile copolymer rubber having an excessive amount of terminal amino groups are used as adhesion promoters in the presence of a plasticizer. We have discovered that a mastic adhesive composition that satisfies the intended purpose can be obtained by blending an amine adduct obtained by a heating reaction with a polyamide resin having an amine equivalent of 50 to 350, preferably 100 to 250. The invention was completed. The above polyvinyl chloride (PVC) used in the present invention
As for the plastisol, those for ordinary plastisol produced by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, etc. may be used. The amount used is usually 2-20
% (weight % with respect to the composition of the present invention, the same applies hereinafter),
Preferably, it should be selected within the range of 3 to 10%. 20
If it exceeds %, there is a tendency for rust to develop due to dehydrochloric acid removal.
Moreover, if it is less than 2%, there is a problem in adhesion. The synthetic rubber used in the present invention includes butadiene rubber, isoprene rubber, chloroprene rubber,
Diene-based rubbers such as butadiene-acrylonitrile copolymer rubber (NBR) and styrene-butadiene copolymer rubber (SBR) may be used.
Particularly effective in absorbing vibration and sound due to rubber elasticity.
NBR and SBR are preferred. The amount used is usually 3-20
%, preferably in the range of 5 to 10%. If it exceeds 20%, the viscosity of the composition will become very high and the workability (dispensability) during adhesive application will be significantly reduced, and if it is less than 3%, the effect of imparting rubber elasticity will hardly be recognized. The plasticizer used in the present invention is one that can swell and dissolve both polyvinyl chloride and synthetic rubber, and specifically includes phthalate esters and petroleum fractionation products, such as DOP, DBP, DIDP, and BBP. ,
Examples include DIOP, DHP, and higher alcohol phthalates. The amount used is usually 10-50%, preferably
It may be selected within the range of 20 to 40%. The fillers used in the present invention are for adjusting physical properties, fluidity, and economic efficiency, and are not particularly limited, and include ordinary inorganic fillers and organic fillers, such as calcium carbonate, clay, talc, Examples include silica powder, cellulose powder, and resin powder. Usage amount is usually 30-60%, preferably 40-50%
It can be set within the range of . Blocked isocyanate, which is a component of the adhesion promoter in the present invention, refers to the active isocyanate group (NCO) of an isocyanate compound with phenol,
Refers to substances blocked with alcohols, oximes, lactams, active methylene compounds, etc. These are inert and do not react at room temperature, but become activated at high temperatures. The above-mentioned isocyanate compounds include aromatic isocyanates, aliphatic isocyanates, and pre-reactants having active free NCO obtained by reacting an excess amount of isocyanate compounds with active hydrogen-containing compounds, specifically TDI, MDI,
HMDI, XDI, hydrogenated MDI, hydrogenated TDI, polyisocyanate reacted with trimethylolpan,
and polyalkylene ether polyols, polyalkyl ester polyols, acrylic polyols, castor oil derivatives, polyamine polyols,
Examples include urethane repolymers reacted with terminal hydroxyl group-modified liquid rubbers (butadiene, acrylonitrile-butadiene, etc.). Specific examples of the compound (thermally dissociable compound) used in the above block include ethanol, n-propanol, n-butanol,
Phenol, cresol, ε-caprolactam,
Examples include methyl ethyl ketone oxime, benzophenone oxime, cyclohexanone oxime, acetone oxime, ethyl malonate, ethyl acetoacetate, and acetylacetone. In the present invention, preferred blocked isocyanates from the viewpoint of storage stability, curability, etc. are MDI, TDI, hydrogenated
A urethane prepolymer reacted with MDI and/or a polyalkylene ether polyol is blocked with ε-caprolactam, methyl ethyl ketone oxime or cyclohexane oxime. In producing such a blocked isocyanate, the thermally dissociable compound may be reacted in an amount of 1.0 to 1.3 equivalents per mole of NCO of the isocyanate compound. The amine adduct, which is a component of the adhesion promoter in the present invention, is obtained by heat-reacting a liquid epoxy resin and a butadiene-acrylonitrile copolymer rubber (NBR) having an excessive amount of terminal amino groups in the presence of a plasticizer. point to. Examples of the liquid epoxy resin include bisphenol A diglycidyl ether type epoxy resin, nopolak type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, linear aliphatic epoxy resin, and epoxy-modified liquid rubber. In particular, those having an epoxy equivalent of 180 to 500 are preferred. NBR with the above terminal amino group (hereinafter referred to as amine-modified NBR)
For example, the acrylonitrile content
Examples include those with an amine equivalent of 800 to 1300 obtained by reacting an alicyclic polyamino compound (such as N-aminoethylpiperazine) or an aliphatic polyamine compound to both ends of NBR with a molecular weight of 10 to 30 mol% and a molecular weight of 2800 to 3500. Commercially available products are Ube Industries' product names ``Hiker ATBN 1300 x 16'' and ``Hiker ATBN 1300 x 21''. Such amine adducts are made by blending liquid epoxy fat and amine-modified NBR in a ratio such that the active hydrogen of the amine is in excess (for example, 2 moles) per equivalent of epoxy, and adding this to a plasticizer (for example, a phthalate ester such as DOP). After dissolving, 2, as a catalyst
It is produced by reacting a tertiary amine compound such as 4,6-tris(dimethylaminomethyl)phenol (DMP) for 30 minutes or more while stirring at a temperature of 40 to 180°C. Preferred reaction conditions include 150° C. for about 1 hour. The polyamide resin which is a component of the adhesion promoter in the present invention has an amine equivalent of 50 to 500, preferably
100 to 250 may be used. For example, in addition to the usual condensation of fatty acids and polyamines, urethane-modified polyamide resins, epoxy group-containing NBR polyamide resins, carboxyl group Containing NBR-based polyamide resins and high-grade dihydrochloric acid-modified polyamide resins are preferably used. The adhesion promoter in the present invention is composed of the above ingredients, and the blending ratio of these ingredients is usually
They may be selected so that the amount of HCO is 1 to 5 moles, the amount of component amines is 0.5 to 3 moles, and the amount of component amines is 4 to 10 moles. The amount of adhesion promoter consisting of ~ components is usually 1 to 15%, preferably 3 to 10%.
It is sufficient to select within the range of . The mastic adhesive and composition of the present invention having the above structure can be advantageously applied especially to specially treated steel plates coated with anti-corrosion oil in automobile assembly lines. After the outer and inner panels are put together and spot welded, the electrodeposition paint is cured at the same time as the next step, when the electrodeposition paint is baked and cured. Next, the present invention will be specifically explained with reference to Examples. Production example 1 (Production of blocked isocyanate) 38.5 g of hydrogenated MDI and 32 g of polyalkylene triol (trifunctional, hydroxyl group equivalent: about 380) are reacted with stirring at 80°C for 20 hours to obtain a urethane prepolymer with an NCO content of about 8%. . Next, methyl ethyl ketone oxime was added to 100 g of this urethane prepolymer.
20.7g was gradually added and reacted under heating at 80℃,
Obtain blocked isocyanate. Production example 2 (Production of amine duct) Bisphenol A dicrycidyl type epoxy resin (manufactured by Ciel Chemical Co., Ltd., Epicote 871, epoxy equivalent
After dissolving 4 g of 390-470) and 20 g of amine-modified NBR (manufactured by Ube Industries, Ltd., Hiker AIBN1300×16, NBR acrylonitrile content 10 mol%, amine equivalent 1200) in 20 g of plasticizer (DOP), a tertiary amine compound Add 0.1 g of (DMP-30), raise the temperature with stirring, and react for 1 hour under heating at 150°C to obtain an amine adduct in which epoxy resin is added to amine-modified NBR. Example 1 component g PVC (manufactured by Kanebuchi Chemical Co., Ltd., PSH-10) ...5 NBR (manufactured by Nippon Zeon Co., Ltd., Nipole DN-214)
...6 SBR (manufactured by Nippon Zeon Co., Ltd., Nipole 1009) ...2 Plasticizer (DOP) ...30 Blocked isocyanate of Production Example 1 ...3 Amine adduct of Production Example 2 ...4 Polyether urethane modified polyamide resin (ACR) manufactured by ACR-3189, amine equivalent 120)
...1 Calcium carbonate ...40 Others (stabilizer, crosslinking aid, moisture absorbent, etc.) ...4 The above components are weighed and blended into a kneader, and stirred and mixed to obtain a mastic adhesive composition. The results of testing the viscosity and adhesion of such compositions at curing temperatures of 130°C or 180°C are shown. Comparative Example 1 In the ingredients of Example 1, an epoxy resin (manufactured by Ciel Chemical Co., Ltd., Epicoat #828) and a curing agent (dicyandiamide,
A mastic adhesive composition was obtained in the same manner except that dimethylurea) was used, and the viscosity and adhesion results are also shown in Table 1. 【table】

Claims (1)

[Scope of Claims] 1. A mastic adhesive comprising polyvinyl chloride, synthetic rubber, a plasticizer, and a filler, comprising: a blocked isocyanate, a liquid epoxy resin, and an excessive amount of butadiene-acrylonitrile copolymer rubber having terminal amino groups. , an amine adduct obtained by heating reaction in the presence of a plasticizer, and a polyamide resin having an amine equivalent of 50 to 350. 2. The composition according to item 1 above, wherein the components are blended in such proportions that the amount of NCO in the blocked isocyanate is 1 to 5 moles, the amount of amine in the amine adduct is 0.5 to 3 moles, and the amount of amine in the polyamide resin is 4 to 10 moles.